Diesel engine use for passenger car applications is increasing due to the benefit of better fuel economy. Further, gasoline engines are increasing compression ratios to improve the fuel efficiency. As a result, diesel and gasoline engine accessory drive systems have to overcome the vibrations of greater magnitude from crankshafts due to above mentioned changes in engines.
Due to increased crankshaft vibration plus high acceleration/deceleration rates and high alternator inertia the engine accessory drive system is often experiencing belt chirp noise due to belt slip. This will also reduce the belt operating life.
Crankshaft isolators/decouplers and alternator decouplers/isolators have been widely used for engines with high angular vibration to filter out vibration in engine operation speed range and to also control belt chirp.
Representative of the art is U.S. Pat. No. 8,534,438 which discloses a decoupler with driven and driving members, a clutch, a torsional vibration damper and a lubricant. The clutch is received in a bore in the driven member and includes a carrier, a wrap spring and at least one spring. The wrap spring is formed of spring wire and has a plurality of coils disposed between a first end, which is received in a groove in the carrier, and a second end. The portion of the wrap spring outside the carrier has an outer circumferential spring surface that is abutted against the inner circumferential surface of the bore. The at least one spring is disposed between the carrier and the driving member to transmit rotary power from the driving member to the carrier. The torsional vibration damper is coupled to the driving member for rotation therewith. The lubricant is disposed on the remaining portion of the wrap spring.
What is needed is an isolating decoupler comprising a sealing member that radially expands under acceleration to sealingly contact the pulley. The present invention meets this need.